Means for use in prestressing concrete structures



Sept. 3, 1963 R. DRUCKER' 3,102,312 MEANS FOR use IN PRESTRESSINC CONCRETE STRUCTURES Filed Nov- 2. 1961 v s Shegts-Sheefi 1 P 3, 963 R. DRUCKER 3,102,312

MEANS FOR USE IN PRESTRESSING CONCRETE ST Flled Nov. 2

Sept. 3, 1963 3,102,312

MEANS FOR USE IN PRESTRESSING CONCRETE STRUCTURES R. DRUCKER s Sheets-Sheet 5 Filed Nov. 2, 1961 the clip shown in FIGURE 4.

I 3,102,312 MEANS FORUSE IN PRESTRESSING CONCRETE STRUCTURES Rudolph Drucker, London, Englandyassignor to G.K.N.

I Reinforcements Limited sn ethwick, England, a Britthrough a concrete member and" have a high tensile stress applied tothem which is subsequently transferred to the concrete with the result that the concrete is under compression in the longitudinal direction of the wires. This techniqueand the advantages thereof; are generally wellknown and understood r The invention is concerned with the case where the tension member comprises a multi-wire strand tension member of the type described and claimed in my copending application Serial No. 149,703."

The object of the invention is to provide an improved form of anchorage device for use in holding the ends of multi-wire strands of thetype above referred to so that the required tensile stress may be applied.

According to the invention we provide an anchorage device for pre-stressed concrete structures for gripping the ends of drawn wire tension members in contact side by side in at least two rows, the wires in adjacent rows being staggered in relation to each other and in direct contact, and comprising a rectangular outer frame having an opening of rectangular cross-section extending therethrough and co-operating fixed and movable wedge members within said opening toapply a grip to the assembly of the ends of the wires, andwherein two opposed movable wedge member engage directly the outermost faces of the rows of wires and .two slidable packing pieces are disposed so as .to contact the wires at the ends of the rows, being disposed in between these wires and the adjacent side walls of the outer frame" and being engaged with the movable wedge members so as to slide relatively I to the frame in unison with the movable wedge members.

The invention is illustrated in. the accompanying drawings wherein:

United States Patent 3,102,312 Patented Sept. 3, 1963 ice 21 amounts to a series of S bends connected together with erably resiliently gripped therein by forming the com- FIGURE 1 is an end view of an anchorage device holding one end of a multi-wire strand tension member.

FIGURE 2 is a section on the line 2-2 of FIGURE 1 the tension member being omitted. I

FIGURES is a section on the line 3-3 of FIGURE 2,

the tension member being omitted.

FIGURE 4 is a perspective view of a clip for securing together the wires in the tension member.

FIGURE 5 is a diagrammatic illustration of the use of FIGURES 6 and 7 illustrate another form of clip. Referring to FIGURE 1, the tension member shown there by way of example comprises a plurality ofwires p all of the same diameter and arranged in three superf posed rows the wires in each row being straight and parallel toone another and as shown, there are five wires indicated at 10 in the upperfrow, four wires at 11 in the middle row and five. wiresindicated at 12 in the lower row. It will be observed from FIGURE 1 that the crosssection of the multi-wire strand. tension member is such that it is bounded by a rectangle.

FIGURE 4 illustrates one form of clip which may be used for securing together the wires in such tension member and this clip is formed from a metal strip 21 which has been bent to form two rows of superposed plete clip from a suitable metal-strip having inherent resilience. p

The use of the clip illustrated in FIGURE 5 is applied to the tension member having three superposed rows audit will be observed that the clips are used at spaced positions along the length of the tension member, some of the clips beingused to hold the wires 10 and 11 in the upper and middle rows and the other of the clips being used to hold the wires 11 and 1.2 in the middle and lower rows thus connecting all three rows together.

Another form of clip is shown in FIGURES 6 and 7, the one part of the clip shown in FIGURE '6, being formed from a length of resilient metal strip which is bent to substantially sinusoidal form so as to provide a number of side by-side pockets 30 each having slots 31 in opposed sides with the portions 32 between the slots being each of substantially semi-circular form. At each end of the strip there is a half portion 32 the edge of which is stepped as shown at 33.

The complete clip shown in FIGURE 7 comprises an exactly similar part inter-engaged with the part shown in FIGURE 6. The wires are placed in the pockets 30 of the clip part A and then clip part B is slid along the wires until its slots 31 interlock with the slots 31 of the part A when it will be observed that the portions 32 of the two parts come together to define substantially circular pockets 34 each containing a Wire and then stepped portions 33 at the end of the clip parts are also inter-engaged.

inbefore. described has a cross-section which is bounded by a rectangle. 7

Considering the position of the anchorage device shown in the drawings, the upper and lower faces of the rec tangular opening 15 through the outer casing 14 are each provided with a fixed wedge member 16 which extends from end-to-end of the casing and is located centrally between the opposed vertical sides of the opening so that on each side of each wedge member .16 there is a clearance gap 1-7 (see FIGURE 3) between the side face of the wedge; member and the adjacent vertical side of the openmg Each movable wedge member 118 is a separate loose wedge member which, when in position, is in wedging engagement in the space between the upper (or lower) face of the multi-wire strand and the adjacent inclined face of theco-operating fixed wedge member 16.

Each movable wedge member 18 is of substantial I form so that at each end it has laterally projecting portions 19, thus providing two elongated gaps one along each side of each wedge member 18 and these gaps are occupied by packing pieces .20 each of which is in the form of a slab of square or rectangular form; each such packing piece 20 being located at its upper edge in the appropriate gap '17 on the side of the upper wedge member :16 and at its lower edge in the similar gap -17 on the adjacent side of the lower wedge member 216. Consequently, when the movable wedge members 18 are forced into wedging engagement to secure the multi-wire strand inside the casing, the two packing pieces 20 also move with the movable wedge members 18 and thus obviate any rubbing contact between the side wires of the multi-wire strand and the adjacent sides of the opening 15 in the outer casing of the anchorage device.

The above described tension member and clips for use therewith, form the subject of my co-pending application Serial No. 149,703.

What I claim then is:

1. An anchorage device for pre-stressed concrete structures for gripping the ends of drawn wire tension members in contact side by side in at least two rows, the wires in adjacent rows being staggered in relation to each other and in direct cont-act, and comprising a rectangular outer frame having an opening of rectangular cross-section extending therethrough, fixed and movable wedge members within said opening to apply a grip to the assembly of the ends of the wires, and wherein two opposed movable wedge members engage directly the outermost faces of the rows of wires and two slidable packing pieces are disposed so as to contact the wires at the ends of the rows, being disposed in between these wires and the adjacent side walls of the outer frame and being engaged with the movable wedge members so as to slide relatively to the frame in unison with the movable wedge members.

2. An anchorage device according to claim 1 wherein each movable wedge member is of substantially I shape with the packing pieces being accommodated on opposite sides of the movable wedge members in the gaps formed between the projecting ends of the movable wedge mem- References Cited in the file of this patent UNITED STATES PATENTS 284,276 Chantrell Sept. 4, 1883 441,026 Sharpneck Nov. 18, 1890 1,951,687 Zapf Mar. 20, 1934 2,449,955 Sanderson et a1 Sept. 21, 1948 2,674,772 Zacobs Apr. 13, 1954 2,781,658 Dobell Feb. 19, 1957 FOREIGN PATENTS 935,972 Germany Dec. 29, 1955 

1. AN ANCHORAGE DEVICE FOR PRE-STRESSED CONCRETE STRUCTURES FOR GRIPPING THE ENDS OF DRAWN WIRE TENSION MEMBERS IN CONTACT SIDE BY SIDE IN AT LEAST TWO ROWS, THE WIRES IN ADJACENT ROWS BEING STAGGERED IN RELATION TO EACH OTHER AND IN DIRECT CONTACT, AND COMPRISING A RECTANGULAR OUTER FRAME HAVING AN OPENING OF RECTANGULAR CROSS-SECTION EXTENDING THERETHROUGH, FIXED AND MOVABLE WEDGE MEMBERS WITHIN SAID OPENING TO APPLY A GRIP TO THE ASSEMBLY OF THE ENDS OF THE WIRES, AND WHEREIN TWO OPPOSED MOVABLE WEDGE MEMBERS ENGAGE DIRECTLY THE OUTERMOST FACES OF THE ROWS OF WIRES AND TWO SLIDABLE PACKING PIECES ARE DISPOSED SO AS TO CONTACT THE WIRES AT THE ENDS OF THE ROWS, BEING DISPOSED IN BETWEEN THESE WIRES AND THE ADJACENT SIDE WALLS OF THE OUTER FRAME AND BEING ENGAGED WITH THE MOVABLE WEDGE MEMBERS SO AS TO SLIDE RELATIVELY TO THE FRAME IN UNISON WITH THE MOVABLE WEDGE MEMBERS. 